The present invention relates to an apparatus for and a method of testing the maneuverability of a vehicle on a test bench.
A flat belt type chassis dynamo is now proposed in order to evaluate the maneuvering stability of the vehicle, substituting for a conventional drum type chassis dynamo. For example, Japanese Patent Unexamined Publication No. 6-249753 discloses a method in which support parts are provided on the upper surfaces of movable parts which can be swung by first hydraulic jacks actuated independent from one another, and can be swung widthwise of the vehicle by second hydraulic jacks actuated independent from one another, corresponding to wheels of a vehicle, and flat belts making contact with the wheels of the vehicle are provided respectively to the support parts, the movable parts being inclined so as to reproduce a climbing slope and a ramp and the support parts being inclined so as to variously change ground contact conditions of the wheels of the vehicle so as to reproduce various disturbances given from the road surface, thereby precisely testing the maneuverability of the vehicle in various road surface conditions over a wide range.
During actual running of a vehicle, dynamic load variation occurs at each of wheels of a vehicle during acceleration or turning, in addition to static load variation caused by a climbing slop or a ramp as mentioned above. For example, during acceleration, loads at rear wheels become larger while during deceleration, loads at front wheels become larger, and during turning, loads at outer wheels become larger. These occur irrespective of a load configuration such as a flat road or a ramp. During acceleration, an inertia force is exerted to the gravitational center of the vehicle while a drive force is exerted to the ground contact points of tires, and accordingly, moments are generated around the pitching axis. Load displacements from the front wheels to the rear wheels occur, corresponding to forces balancing the above-mentioned pitching moments. Similarly, a centrifugal force is exerted to the gravitational center of the vehicle during turning while a cornering force is exerted to a ground contract point, and a rolling moment is effected. A displacement of a load from an outer wheel to an inner wheel occurs, corresponding to a force balancing with the rolling moment.
Further, the wheels (tires) stroke vertically while they are guided by suspension links. Since the links have a limited length, the alignment with respect to the road surface is always changed as the wheels stroke.
The variation in load and variation in the alignment for tires intricately influence upon each other so as to excessively affect the friction forces between the tires and the road surfaces, and cause influence factors which are not negligible for analyzing the maneuverability of the vehicle, in particular abrupt change in maneuvering.
For example, in such a case that a vehicle is arrested in the longitudinal direction thereof on a four wheel flat belt type chassis dynamo, no longitudinal displacement of the vehicle does not occur on the test bench. That is, the longitudinal maneuver is restrained. Accordingly, no moment caused by an inertia force and causing the load variation and the alignment variation is produced. A traction force exerted between each tier and the associated flat belt is exerted to the vehicle arresting device, and accordingly, a reaction force thereto is exerted to the vehicle so that a pitching moment caused by the traction force and the reaction force transmitted from the is finally exerted to the vehicle. If the vehicle arresting device arrests the vehicle at the height of the gravitational center of the vehicle, a pitching moment equal to that during running can be exerted thereto, but if the vehicle arresting device arrests the vehicle at a height lower than the height of the gravitational center, the pitching moment becomes smaller. Thus, the load variation become smaller than that during running.
The present invention is devised in view of the above-mentioned load variation and alignment variation, and accordingly, one object of the present invention is to provide a testing apparatus for and a testing method which can precisely analyze a maneuverability of a vehicle, and in particular a variation in maneuver of the vehicle.
In a method for carrying out load variation and alignment variation on a test bench, it is required to exert forces representing an inertia force upon acceleration or deceleration and a centrifugal force upon turning, during actual running, to a vehicle, and to adjust these forces in accordance with a load variation and an alignment variation caused thereby.
To the end, according to the present invention, there is provided a vehicle testing apparatus for testing a vehicle on a test bench incorporating dummy road surface means instead for a road surface, comprising means for measuring a relative force between the test bench and the vehicle, and an actuator adapted to be driven in accordance with a force measured by the force measuring means,, for applying a force to the vehicle.
Further, according to the present invention, there is provided a vehicle testing apparatus for testing a vehicle on a test bench incorporating dummy road surface means instead of a road surface, comprising means for measuring a relative force between the test bench and the vehicle, and an actuator adapted to be driven in accordance with a force measured by the force measuring means, for applying a force to the vehicle, wherein the dummy road surface means is driven in accordance with the force measured by the force measuring means.
In the above-mentioned vehicle testing apparatus, the actuator is preferably driven so as to produce a moment around a crosswise (widthwise) axis in accordance with a component longitudinal of the vehicle, measured by the force measuring means.
Further, in the above-mentioned vehicle testing apparatus, the actuator is preferably driven so as to produce a moment around the crosswise (widthwise) axis of the vehicle in accordance with a force exerted to the gravitational center of the vehicle in the longitudinal direction of the latter, a height of the gravitational center of the vehicle, a wheel base of the vehicle.
Further, in the above-mentioned vehicle testing apparatus, the dummy road surface means is driven by the actuator so as to apply a force to the vehicle.
Further, according to the present invention, there is provided a vehicle testing method in which a vehicle is tested on a bench incorporating dummy road surface means used instead of a road surface, comprising the steps of detecting a relative force between the test bench and the vehicle, applying a force to the vehicle by means of an actuator in accordance with the detected force.
Further, according to the present invention, there is provided a vehicle testing method in which a vehicle is tested on a bench incorporating dummy road surface means used instead of a road surface, comprising the steps of detecting a relative force between the test bench and the vehicle, applying a force to the vehicle by means of an actuator in accordance with the detected force, and driving the road surface means in accordance with a relative force between the test bench and the vehicle.
In the above-mentioned vehicle testing method, a force component longitudinal of the vehicle is preferably measured, a moment around a crosswise axis of the vehicle is calculated from the force component, and the actuator is driven so as to produce this moment.
Further, in the above-mentioned vehicle testing method, a force longitudinal of the vehicle, exerted to the gravitational center of the vehicle, is preferably measured, a moment around a crosswise axis of the vehicle is calculated from the force, a height of the gravitational center and a wheel base of the vehicle, and the actuator is driven so as to produce this moment.
Further, in the above-mentioned vehicle testing method, a the dummy road surface means is driven by the actuator so as to exert a force the vehicle.
According to the present invention, since a force is applied to the vehicle, in accordance with a relative force between the test bench and the vehicle, measured by the force measuring means, load variation of the vehicle, and alignment variation of tires caused by suspension stroke can be effected during testing.